Matlab Software:

Matlab can be used from home through "virtual lab":
virtual lab
It is also available on Windows in the general student labs, see
http://www.uwo.ca/its/genlabs/ for general lab locations.
There is some freely available software on the web, however it is your responsibility to make sure your code compiles in the matlab (you can check so by using a university lab)
The information below is cortesy Karim (thanks!)

Scilab:
Close to matlab, but not really compatible (for example : matrice creation : it uses commas instead of spaces to separate values on the same row), but there is converters from matlab to scilab and the other way.